1. Field of the Invention
The present invention relates generally to construction equipment, and more particularly is a ladder mounted elevator device to raise loads.
2. Description of the Prior Art
People in the construction and building service industries are well aware of the many items that need to be raised to the roofs of various structures. The most common items to be lifted are of course the items that are installed on the roofsxe2x80x94roofing materials and heating, ventilating, and air conditioning equipment. These items are usually far to heavy to simply be carried up a ladder by a workman.
Various pieces of equipment have been utilized to resolve the elevating problem, among them cranes, cherry pickers, and helicopters. While these machines are certainly effective in raising the required loads, they are also expensive to operate, sometimes prohibitively so. Moreover, these machines require operating manpower in addition to that required for the actual installation at hand.
The prior art discloses many devices that have been proposed to address the problems of raising loads to a rooftop or to another elevated location. Various ladder hoists, hoist attachments, and ladder attachments to facilitate lifting have been offered for use in the painting, maintenance, HVAC, and construction trades.
Many such devices are essentially winches attached to a ladder, such as the xe2x80x9cLifting Device for Use with a Ladderxe2x80x9d by Campbell, U.S. Pat. No. 5,911,287, issued Jun. 15, 1999. Another such device is the xe2x80x9cLadder Hoist Attachmentxe2x80x9d of Larson, U.S. Pat. No. 4,598,795, issued Jul. 8, 1986. Still another is the xe2x80x9cStabilized Ladder Power Winch Systemxe2x80x9d of Pate, U.S. Pat. No. 5,139,108, issued Aug. 18, 1992. Still another is the xe2x80x9cExtension Ladder Hoistxe2x80x9d of Ziegelmann, U.S. Pat. No. 4,128,228, issued Dec. 5, 1978.
Other lifting devices incorporate a ladder or a ladder-like element with a hoist support arrangement to yield a portable hoist. One such device is the xe2x80x9cLift and Portable Liftxe2x80x9d of Krotov, et al., U.S. Pat. No. 5,427,356. A similar device is the xe2x80x9cPortable Hoistxe2x80x9d of Killeen, U.S. Pat. No. 4,690,248, issued Sep. 1, 1987. A device that connects the hoist support to the terminal end of a ladder is the xe2x80x9cPortable Swiveling Lift Devicexe2x80x9d of Sears, U.S. Pat. No. 5,738,185, issued Apr. 14, 1998.
The lack of widespread use of these prior art devices is attributable to their having one or more of the following shortcomings: (1) insufficient anchoring of the base of the ladder; (2) insufficient stabilization of the portion of the ladder from which the lifting force is applied; (3) lack of a safe and secure means of securing the upper end of the ladder; (4) the failure to provide sufficient power and mechanical advantage to lift large loads; (5) lack of easy portability; and (6) lack of compatibility with existing ladders.
Accordingly, it is an object of the present invention to provide a ladder elevator device that can be affixed to a standard ladder.
It is another object of the present invention to provide a device that has a stable base.
It is still another object of the present invention to provide a device that has adequate means of securing the lifting device to the roof top or other elevated area.
It is yet another object of the present invention to provide a device that is easily portable, but has adequate lifting power.
These and other objects and advantages of the present invention will become apparent to those skilled in the art in view of the description of the best presently known mode of carrying out the invention as described herein and as illustrated in the drawings.
The present invention is an elevator device that is installed on a standard ladder, or for large lifting capacity installation, two or more ladders. In applications using two or more ladders, a base securing device can be added to each of the ladders to insure stability.
The elevator device includes a ladder attachment assembly to affix the device to a ladder or ladders, a lateral travel section, and a roof top mounting device utilizing a T-bar support arm. A ladder stabilization bracket can be employed that affixes the ladder to a parapet or balcony for additional stability of the device.
A winch raises the load from the ground, and then moves along the lateral travel section to provide lateral travel for the load on the roof top. If desirable for a particular job, extension elements can be added to the lateral travel section so that the winch extends further onto a roof to reduce transport labor.
The device can be easily adapted for use on flat roofs with a parapet through the addition of a ladder stabilization bracket. The elevator device can also readily be used on flat roofs without parapets, pitched roofs, and even to load trucks.
The ladder elevator device of the present invention will typically be operated by a handheld control panel. Depending on the preference of the user, a foot operated control panel is also provided.
Another useful implementation of the present invention that should be noted, apart from the main function of a single elevator raising a load, is that two of the elevator devices can be employed in tandem to form a convenient portable and automated scaffold device.
An advantage of the present invention is that it is easily attached to all common ladders.
Another advantage of the present invention is that it is sturdy enough to have a very large lifting capacity.
A still further advantage of the present invention is that it includes a means to move the load across a rooftop, rather than to just lift the load to the roof.
Still another advantage of the present invention is that it has a means to secure the travel section of the device securely on the rooftop or other elevated area.
These and other objects and advantages of the present invention will become apparent to those skilled in the art in view of the description of the best presently known mode of carrying out the invention as described herein and as illustrated in the drawings.